An abstract class that handles the loading of protocol-specific URL data.
SDKs
- iOS 2.0+
- macOS 10.2+
- tvOS 9.0+
- watchOS 2.0+
Framework
- Foundation
Declaration
class URLProtocol : NSObject
Overview
Don’t instantiate a URLProtocol subclass directly. Instead, create subclasses for any custom protocols or URL schemes that your app supports. When a download starts, the system creates the appropriate protocol object to handle the corresponding URL request. You define your protocol class and call the register class method during your app’s launch time so that the system is aware of your protocol.
To support the customization of protocol-specific requests, create extensions to the URLRequest class to provide any custom API that you need. You can store and retrieve protocol-specific request data by using URLProtocol’s class methods property(for and set.
Create a URLResponse for each request your subclass processes successfully. You may want to create a custom URLResponse class to provide protocol specific information.
Subclassing Notes
When overriding methods of this class, be aware that methods that take a task parameter are preferred by the system to those that do not. Therefore, you should override the task-based methods when subclassing, as follows:
Initialization — Override
init(task:instead of or in addition tocached Response: client:) init(request:. Also override the task-basedcached Response: client:) caninstead of or in addition to the request-basedInit(with:) can.Init(with:)